1. Field of the Invention
The present invention relates to a power amplifier for use in a portable telephone terminal or the like.
2. Background Art
A bias circuit of a power amplifier has a transistor that supplies a bias to the base of the amplifier according to an on/off signal. Also, a capacitor connected between the base of the amplifier and a grounding point is provided for the purpose of reducing low-frequency noise (see, for example, Japanese Patent Laid-Open No. 2004-134826). At the moment at which the on/off signal is changed from the on signal to the off signal, the amplifier is still maintained in the on state by electric charge accumulated in the capacitor. Thereafter, when the electric charge in the capacitor is discharged through a resistor, the amplifier is turned off.